An Asian elephant named Koshik has learned to speak Korean by using his trunk and mouth to vocalise words.
Koshik can imitate human speech and can be understood by people who understand Korean. He can say hello, sit down, no, lie down and good.
It is unclear why the elephant began to speak, but researchers think it may hark back to his infancy, as he was the only elephant living at the Everland Zoo in the South Korean city of Yongin.
For around five years, during an important bonding period, Koshik's only social contacts were humans.
Angela Stoeger, from the University of Vienna, said: "We suggest that Koshik started to adapt his vocalisations to his human companions to strengthen social affiliation, something that is also seen in other vocal-learning species - and in very special cases, also across species."
In the past, there have been reports of African and Asian elephants vocalising sounds. African elephants have been known to imitate truck engines, while one Asian elephant from a zoo in Kazakhstan is believed to have said words in both Russian and Kazakh.
Stoeger said: "Human speech basically has two important aspects, pitch and timbre.
"Intriguingly, the elephant Koshik is capable of matching both pitch and timbre patterns: he accurately imitates human formats as well as the voice pitch of his trainers.
"This is remarkable considering the huge size, the long vocal tract, and other anatomical differences between an elephant and a human."
Koshik's speech mimics exact copies of the pitch and other characteristics of his human trainers' voices. Structural analysis of his 'voice' showed clear similarities to human voices.
The researchers asked native Korean speakers to write down what they heard when they listened to recordings of Koshik.
Stoeger said: "We found a high agreement concerning the overall meaning, and even the Korean spelling of Koshik's imitations."
It is thought Koshik's ability to speak could provide an insight into the biology and evolution of complex vocal learning, an ability crucial to human speech.